<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    
</head>

<body>
    <div id="app">
        商品的数量：<input type="text" v-model="count"><br>
        商品的单价：<input type="text" v-model="price"><br>
        <p>商品的总价：{{count * price}}</p>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.14"></script>
    <script>
        new Vue({
            el: "#app",
            data() {
                return {
                    count: 8,
                    price: 9.9
                }
            }
        })
    </script>
</body>

</html>